Introduction to AI Speech Synthesis: Making Text Speak with APIs

2026/06/09·6 min read·74 views

Have you ever thought about having AI turn a piece of text into natural, fluent speech? Whether you are creating audiobooks, dubbing videos, or building a voice assistant, Text-to-Speech (TTS) technology can help you achieve it. This article will guide you step by step on how to call the TTS service through the Ciyuan Circle API, so even beginners can get started quickly.

What is Speech Synthesis

Speech Synthesis (Text-to-Speech, or TTS) is a technology that converts text into speech. Simply put, you give the AI a piece of text, and it can "read" it aloud, with voices sounding increasingly natural.

Modern TTS technology can already achieve:

Natural and fluent: No longer mechanical electronic voices; it sounds like a real person reading
Multiple timbres: Choose freely from male voices, female voices, and different styles
Multilingual support: Can handle mainstream languages like Chinese, English, Japanese, etc.
Emotional expression: Adjusts tone and emotion based on the content

TTS API Call Flow

Preparation

Before you start, you need to prepare the following:

Ciyuan Circle account: Visit ciyuano.com/register to register
An API key: Create one in the "API Keys" page in the backend
An HTTP client: You can use curl (command line), Postman, or any programming language

Tip: The TTS function requires sufficient balance in your account. New users usually have free credits; you can check in the "Usage" page in the backend.

Choosing the Right Voice

Ciyuan Circle supports multiple voice timbres, each with different stylistic features. Below is a comparison of commonly used timbres:

Comparison of Common Voices

Suggestions for choosing a voice:

Not sure which one to use? Choose alloy, the most versatile neutral voice
Doing customer service or educational content? Choose nova, warm and friendly
Doing news broadcasting? Choose echo, clear and professional
Telling stories or dubbing? Choose fable, full of emotion

Detailed Steps

Step 1: Obtain the API Key

Log in to the Ciyuan Circle backend, go to the "API Keys" page, and create a new key. Copy the key; the format looks like sk-relay-xxxxxxxxxx.

Security Reminder: The key is only displayed once; please save it properly. Do not hardcode the key in public code repositories.

Step 2: Send a TTS Request

Use the curl command to send a simple TTS request:

curl -X POST https://www.ciyuano.com/v1/audio/speech   -H "Authorization: Bearer sk-relay-YOUR_API_KEY"   -H "Content-Type: application/json"   -d '{
    "model": "tts-1",
    "input": "Hello, welcome to Ciyuano TTS service. What a beautiful day!",
    "voice": "alloy"
  }'   --output speech.mp3

Meaning of this command:

POST /v1/audio/speech: Calls the speech synthesis interface
model: The model used; tts-1 is the standard model, tts-1-hd is the high-definition model
input: The text content to be converted to speech
voice: The selected timbre
--output speech.mp3: Saves the returned audio as an MP3 file

After successful execution, a speech.mp3 file will be generated in the current directory. Open it with any player to hear the AI-generated speech.

Step 3: Adjust Speech Parameters

You can control the speech effect with additional parameters:

{
  "model": "tts-1-hd",
  "input": "This is a test with HD audio quality.",
  "voice": "nova",
  "speed": 1.2,
  "response_format": "mp3"
}

Description of adjustable parameters:

Parameter	Description	Default Value
`model`	Model selection: `tts-1` (standard) or `tts-1-hd` (high-definition)	tts-1
`voice`	Timbre selection: alloy / nova / echo / fable / onyx / shimmer	alloy
`speed`	Speech speed, range 0.25 ~ 4.0	1.0
`response_format`	Output format: mp3 / opus / aac / flac / wav / pcm	mp3

Tip: If the speech speed is not suitable, adjust it with the speed parameter. For example, for audiobook scenarios, you can use 1.2 ~ 1.5x speed; for explanatory scenarios, use 0.8 ~ 1.0x speed.

Step 4: Call from Code

If you are familiar with Python, you can use the following code to call the TTS interface:

import requests

url = "https://www.ciyuano.com/v1/audio/speech"
headers = {
    "Authorization": "Bearer sk-relay-YOUR_API_KEY",
    "Content-Type": "application/json"
}
data = {
    "model": "tts-1",
    "input": "Hello, this is a test voice.",
    "voice": "nova"
}

response = requests.post(url, headers=headers, json=data)

with open("output.mp3", "wb") as f:
    f.write(response.content)

print("Voice generated：output.mp3")

The JavaScript / Node.js approach is similar:

const response = await fetch("https://www.ciyuano.com/v1/audio/speech", {
  method: "POST",
  headers: {
    "Authorization": "Bearer sk-relay-YOUR_API_KEY",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    model: "tts-1",
    input: "Hello, this is a test voice.",
    voice: "nova"
  })
});

const buffer = await response.arrayBuffer();
require("fs").writeFileSync("output.mp3", Buffer.from(buffer));
console.log("Voice generated：output.mp3");

Practical Use Cases

Scenario 1: Batch Generation of Audio Content

If you have a batch of articles to convert to speech, you can write a simple loop script to call the TTS interface segment by segment. Pay attention to controlling the call frequency to avoid triggering rate limits.

Scenario 2: Video Dubbing

When creating tutorial videos, first use TTS to generate the narration audio, then composite it into the video using editing software. This is more efficient than recording yourself and provides more stable audio quality.

Scenario 3: Voice Notifications

Add voice notification functionality to your application, such as order reminders and system alerts. Users will receive warm voice prompts instead of cold text.

Scenario 4: Multilingual Content

Use timbres in different languages to generate multilingual versions of the same content, making it easy to distribute content internationally.

Common Problems

Problem	Solution
Returns 401 error	Check if the API key is correct, or if it has expired or been disabled
Returns 429 error	Requests are too frequent; reduce the call frequency or upgrade your plan
Audio file is empty	Check if the input field is empty or if the text length exceeds the limit
Chinese pronunciation is unnatural	Try switching to a different timbre, or use the tts-1-hd model for better results
Slow generation speed	tts-1 is faster than tts-1-hd; for long texts, consider processing them in segments

Usage Tips

Text preprocessing: Remove unnecessary special characters and formatting symbols to make the speech more natural
Segment processing: For long texts, split them by paragraph or sentence, with each segment not exceeding 4000 characters
Format selection: Use MP3 for everyday use; choose FLAC or WAV if lossless quality is needed
Cache reuse: Cache audio for identical content to avoid repeated calls and extra costs
Compare multiple timbres: When unsure which timbre to use, test multiple timbres with short text

Summary

With the Ciyuan Circle TTS API, you can easily convert text into natural, fluent speech. The entire process only requires three steps:

Obtain an API key
Send an HTTP POST request
Receive and save the audio file

Next Steps: Try reading the same piece of text with different timbres to experience the stylistic differences. Then integrate it into your project to provide users with a better voice experience.

View the full API documentation · Browse all models

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